Updated Major Release: ReCodEx 2.0 (markdown)

Major-Release:-ReCodEx-2.0.md

@@ -1,3 +1,25 @@
 > Major version change denotes a larger leap forward and marks a milestone in development. However, we are not strictly bound with semantic versioning here. Furthermore, the development does not stop here, we still have long road ahead...
 
+## Administrator's Guide To Migration
+
+- Do not forget to perform database migration after `recodex-core` update.
+```
+/opt/recodex-core/bin/console migrations:migrate
+```
+
+- Core module has now service that handles async operations. The service just needs to be started (no special configuration is necessary):
+```
+$> systemctl enable recodex-core.service
+$> systemctl start recodex-core.service
+```
+
+- Add async jobs upkeep maintenance to cron. The upkeep deletes old jobs from the database and makes sure no jobs linger too long (in case the async worker crushes or gets overwhelmed with jobs). If the async worker gets stuck, an email is sent to ReCodEx admin. Recommended upkeep period is 30 minutes, so you need to add the following line into `/etc/crontab` (adjust the paths/user if need be):
+```
+*/30 * * * *    recodex    /opt/recodex-core/bin/console asyncJobs:upkeep
+```
+
+- In the web app configuration file `env.json`, the `"SKIN"` value needs to be updated according to [readme](https://github.com/ReCodEx/web-app/blob/master/README.md). The `skin-` prefix should be removed (e.g., `skin-green` needs to be replaced with `green`).
+
+## New Features
+
 TBA